1. Field of the Invention
The present invention relates to retractable running boards for vehicles.
2. Description of Related Art
Most conventional vehicle running boards have fixed positions relative to the frames of the vehicles that they are attached to.
Designers of fixed-position running board vehicles must balance ground clearance against the desire to place running boards in a lower, more passenger convenient position midway between ground level and the lower edge of the vehicle door opening. In a vehicle such as a truck, in which a large ground clearance is advantageous, the cab and passenger seats are typically disposed well above ground level. Consequently, conventional running boards provide an intermediate step for passengers to use to enter and exit the vehicle. From the standpoint of facilitating a passenger's entrance and exit from the vehicle, the most convenient height for a running board is generally at about half the distance between the ground level and the lower edge of the vehicle door opening. However, disposing the running board at such a low position reduces the vehicle's ground clearance. Consequently, designers must sacrifice either convenience or ground clearance when determining the height of a fixed-position running board.
Conventional retractable running boards, such as the running board disclosed in U.S. Pat. No. 5,697,626, include running boards with selectively variable heights. When the vehicle is being driven, the running board is raised vertically to improve the vehicle's ground clearance. Conversely, when the vehicle is stopped, the running board can be lowered to position the running board at a more convenient height for the passengers.
Vehicle designers face an additional dilemma when determining the lateral position of fixed-position running boards. To provide the most convenience to passengers entering or exiting a vehicle, the running board should be disposed laterally outwardly from the vehicle's entrances/doors such that the lower edge of the door opening, the running board, and the ground form laterally- and vertically-spaced steps like those in building stairways. Unfortunately, disposing a running board fixed laterally outwardly from the vehicle for the passengers' convenience disadvantageously increases the vehicle's width.
Conventional retractable running boards, such as the running board disclosed in U.S. Pat. No. 3,608,957, have been designed to extend laterally outwardly when the vehicle's door is opened such that the running board is in a convenient laterally-outward position when the passengers need to use it to enter and exit the vehicle. Conversely, the running board is retracted laterally inwardly when the door is closed so that the vehicle has a narrower width during operation.
The Applicants are aware of a retractable running board developed by Amp Research of Irvine, Calif. that moves both laterally and vertically between its extended and retracted positions; however, they have not had an opportunity to examine that device, nor are they aware of any patents disclosing that device. The Applicants believe that two longitudinally spaced four-bar linkages connect the running board to the vehicle, and that an automatic actuator powers only one of the two linkages to extend the running board downwardly and outwardly when the vehicle's passenger door is opened. The second four-bar linkage is believed to move freely and therefore follows the movements of the first powered linkage as the powered movement of the first linkage is transferred through the length of the running board to the second linkage. Because the second linkage is not, itself, powered and cannot resist movement of the running board, the running board cannot be firmly held in place, especially when the weight of a passenger is exerted on the running board at a position far from the first powered linkage.
The statements made herein with respect to the Amp Research device are only made for the purposes of disclosing potentially relevant information to the Examiner. As the Amp Research device was only seen at a tradeshow prior to the effective filing date of this application by an employee of the assignee and could not be closely examined, Applicants believe that the device functions as stated above and for the purposes of examining the present application, the Examiner may consider this to be the case. However, Applicants reserve the right to dispute these issues in the event further information becomes available.